Kisiwa Panza — For over 25 years, rising seas linked to climate change have caused repeated flooding on the small island of Kisiwa Panza

First, the encroaching sea started eating away at homes and killing crops on the small island of Kisiwa Panza. Then the rising tides began bringing up the dead.

For over 25 years, rising seas linked to climate change have caused repeated flooding on this remote islet in the Tanzanian archipelago, saturating the land with saltwater.

Islanders say banana trees that used to produce enough fruit to sell by the boatload to Pemba and other neighbouring islands have become barren and died.

Farmers tried planting rice and cassava instead - but nothing would grow in the salt-poisoned soil, they say.

Then the water reached some of Kisiwa Panza's graveyards. People found themselves scrambling to protect the remains of their friends and families.

"We collected the bones, took them to another site in a wheelbarrow and dug them new graves," said Saida Ali Faki, a 35-year-old farmer.

But today, the graveyards lay undisturbed, the houses stand dry and the banana trees are back.

Since 2017, two new concrete seawalls have protected residents from flooding.

And as the walls hold back the water, also people are planting mangrove forests to strengthen the island's natural defences.

With the help of these two defence systems, the people of Kisiwa Panza say they have hope they can stop the rising sea from destroying their island.

Faki remembers a time, before the protection was put in place, when she could only grow enough to feed her eight children once a day.

This year, she planted maize and greens on a small patch of land that used to be regularly swamped with seawater.

"Now the wall is built, I expect to get more crops," she said.

EXPANDING OCEANS

Small islands like Kisiwa Panza bear the brunt of climate change, experts say.

The United Nations' Intergovernmental Panel on Climate Change predicts that global sea levels could rise by close to a metre (3 feet) or more by 2100 due to melting ice and the expansion of oceans as they warm.

A recent study led by the United States Geological Survey, a government agency, showed that in the coming decades, "wave-driven flooding" - when large waves and storm waters wash over an area - could make thousands of low-lying tropical islands uninhabitable.

"My fear is that the small islands and other islands intruded by sea-level rise will be submerged," said Mwalimu Khamis Mwalimu, head of Pemba Island's environment department.

In an effort to stop Kisiwa Panza from being swallowed by the sea, the Tanzanian government built two 25-metre-long (80-foot-long) seawalls on the island in 2017, with support from U.N. agencies and international environmental funds.

The construction of the walls is part of a broader climate change adaptation project led by UN Environment and the U.N. Office for Project Services.

By combining seawalls with a push to rehabilitate wave-slowing mangrove forests and coral habitats, the project aims to help defend Tanzanians in coastal communities against the destructive effects of saltwater flooding.

So far, seawalls have gone up at seven sites on Tanzania's mainland and the islands, including the commercial capital Dar es Salaam, which has a 2.4-km-long barrier protecting businesses and residences.

"I think (the walls) have been very beneficial," said Cletus Shengena, a senior economist in the environment division of Tanzania's vice president's office.

Before the walls went up, many people had to abandon their houses and land due to flooding, Shengena noted.

Now, "with these seawalls, people have gone back", he said - and some are able to farm their land again.

THE MANGROVE DEFENCE

Another key part of protecting the islands is strengthening mangrove forests along the coasts.

Juma Ali Mati, chairman of the local environmental organisation JSEUMA, said for past decade his group been encouraging people to plant mangroves along Kisiwa Panza's coast.

Mangroves act as a buffer against coastal erosion and flooding while they absorb carbon from the air, experts say.

According to Mati, islanders first started noticing the impact of rising sea levels in the early 1990s. Many now believe reforestation is the answer to saving the island.

Taking walks out to the mangrove forests to collect seeds and plant them in the sand has become a part of island life, Mati said.

Those efforts are now getting help from the United Nations-backed adaptation project, which is providing people with seeds and tools and showing them how to set up nurseries to raise mangrove seedlings.

GAINING GROUND

The farmers on Kisiwa Panza say the efforts to protect the island are already bearing fruit.

Mati said before the walls were built, the encroaching seawater had caused his banana yields to fall from about 150 bunches per harvest to as few as 20.

In the year since the wall went up, he has managed to produce around 50 bunches per harvest.

"Since we have constructed this seawall, we can harvest again," he said. "Before, we were trying and getting nothing."

Some experts, however, warn against relying on seawalls as a permanent fix.

For one thing, said Lizzie Yarina, a researcher at the Massachusetts Institute of Technology's Urban Risk Lab, the walls need to be regularly checked and fortified to combat erosion caused by the combination of saltwater and relentlessly lapping waves.

"Seawalls can be problematic because they're built by people who might not be around long term," she said. Sometimes "there is not the local capacity to maintain them over time".

Seawalls can also have the negative effect of pushing the problem of erosion and flooding to nearby areas that aren't protected, Yarina said.

It is an issue that worries Faki.

As she watched her children head off to plant more mangrove seeds, the farmer said she feels islanders are starting to gain ground in their fight against the rising waters. But she knows there is still a long way to go.

Faki would like to see the government provide more stopgaps to protect both the living and the dead.

"If the other areas that have the same problem don't get walls and people don't plant mangroves, the problem of graveyard destruction will continue," she said. (Reporting by Hannah McNeish, Editing by Jumana Farouky and Laurie Goering.

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